One and Three Dimensional Evaluation of Solute Macrodispersion in an Unsaturated Sandy Soil

Abstract

The results from a series of one-dimensional and three-dimensional solute transport studies done at the University of California, Riverside, are reviewed and integrated. It is found that the stochastic-convective lognormal transfer function model (CLT) after a single calibration at 0.3 m provides an excellent simulation of the observed field scale breakthrough curves to a depth of 1.8 m under both transient and steady-state water flow conditions. By 14 m travel distance, the dispersivity appears to be converging to an asymptote for small areas (∼3 m²) within the field but the area-averaged macrodispersivity for the entire 640 m² field continues to grow at this distance. The effect of soil texture changes in this field is to produce oscillations in the longitudinal variance of a solute plume without appreciably increasing transverse dispersion. A method of linking the parameters of the CLT model to changes in soil properties is tested and found to have the potential to improve the original CLT model predictions of solute dispersion beyond the region of variable soil texture.